Hibernate Validator:在注释中使用if - else类型的逻辑

Question

我正在使用像@NotEmpty这样的Hibernate验证器来查看类中的特定属性是否为空.课程如下所示:

@Entity
@Table(name="emergency_messages")
public class EmergencyMessages implements Serializable {

@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="id", nullable=false)
private Integer id;

@NotEmpty(message="Home message cannot be empty")
@Column(name="home_page_message")
private String homePageMessage;

@Range(min=0, max=1, message="Please select one of the display announcement value")
@Column(name="messages_enabled")
private Integer messagesEnabled;
}

到现在为止还挺好.每当属性"homePageMes​​sage"为空时,我都可以在浏览器中看到表单中的正确错误消息.

现在情况发生了变化.新要求是,只有当其他属性"messagesEnabled"设置为1时,属性"homePageMes​​sage"才可以为空.如果设置为0,则"homePageMes​​sage"不应进行空检查.简单来说,"homePageMes​​sage"的验证现在应该依赖于"messagesEnabled"值.

我的问题:这可能与注释有关吗？如果没有,那么我将不得不拆除我的hibernate验证器机制并创建我自己的验证类.

Answer 1

以下是我想出的代码（根据 Ajinkya 和 Alex 的建议）：

自定义注释：

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import javax.validation.Constraint;
import javax.validation.Payload;

@Target({ElementType.TYPE})  
@Retention(RetentionPolicy.RUNTIME)  
@Documented  
@Constraint(validatedBy=HomePageEmptyMessageValidator.class)
public @interface HomePageEmptyMessage {

String message() default "";

 Class<?>[] groups() default {};

 Class<? extends Payload>[] payload() default {};
}

定制验证器：

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;

public class HomePageEmptyMessageValidator implements ConstraintValidator<HomePageEmptyMessage, EmergencyMessages> {

@Override
public void initialize(HomePageEmptyMessage homePageEmptyMessage) {
}

@Override
public boolean isValid(EmergencyMessages emergencyMessages, ConstraintValidatorContext context) {

    if (emergencyMessages == null) {
        return false;
    }

    Integer messageEnabled = emergencyMessages.getMessagesEnabled();
    if (messageEnabled != null) {
        if (messageEnabled == 1) {
            String homePageMessage =  emergencyMessages.getHomePageMessage();
            if (Util.isNullOrEmpty(homePageMessage)) {
                return false;
            } else {
                return true;
            }
        } else {
            return true;
        }
    }

    return false;
}

}

代码中自定义注解的用法：

@Entity
@Table(name="emergency_messages")
@HomePageEmptyMessage(message="Home page annoucement cannot be empty if the Display  Announcement is set to Yes")
public class EmergencyMessages implements Serializable {

private static final long serialVersionUID = -7870767517772161300L; 

@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="id", nullable=false)
private Integer id; 

@Column(name="home_page_message")
private String homePageMessage;

@Range(min=0, max=1, message="Please select one of the display announcement value")
@Column(name="messages_enabled")
private Integer messagesEnabled;
}

我希望它能帮助某人。